1906.] NATURAL SCIENCES OF PHILADELPHIA. 575 



Changes in the Tongue. — On the left side the Asulkan Glacier is 

 bearing a large amount of morainal material which is deposited at the 

 lower part of the left edge and upon the tongue. The right side is 

 comparatively free from moraine except stray erratics which are 

 borne on the surface of the ice and deposited at the edge. Several 

 small moraines on the bed moraine indicate that at one time the 

 amount of this material was much greater than at present. 



For several years the tongue has been deeply bedded in moraine and 

 was difficult to locate. During the period of slight advance which was 

 first noted in 1903 a steep moraine was pushed up at the tongue and the 

 stream forced to find an exit through a smaller moraine on the right. 

 The present year, however (1906), the tongue occupied almost exactly 

 the same position as in 1899, leaving a space between the ice and the 

 moraine which was formed during the glacier advance. A considerable 

 stream issues directly beneath the tongue and almost covering the 

 1899 test rock, has broken through the high unstable moraine. 



The following table shows the changes in the tongue as observed 

 since 1899. 



Table Showing Changes in Tongue of Asulkan Glacier. 



Aug. 12, 1899 "Rock opposite lined with snout." 



Aug. 8, 1900 Snout receded 24 feet. 



Aug. 6, 1901 Ice above rock 20 feet, 4 feet advance. 



Aug. 30, 1903 Ice below rock 16 feet, 36 feet advance since 1901. 



Jul}- 23, 1906 Ice lines with test rocks, or is in same position as in 1899. 



The Flow of Glacier above Tongue. — For this work a line was selected 

 across the glacier about 1,250 feet above the tongue and as nearly as 

 possible at right angles to the line of flow. Owing to the comparatively 

 short distances and the ease of observation no base line was laid down 

 except as a check, and the positions of the plates from the points of 

 observation were determined by means of the stadia. The motion of 

 the plates on the ice was in every case measured with a horizontal 

 steel tape at right angles to the base line. Plates numbered 7 to 12, 

 similar to those used on the Illecillewaet Glacier, were laid out on July 

 13, 1906, and their motion determined on July 23. The following 

 table shows the total and average daily motion of the plates and of a very 

 large oblong bowlder resting on the top of the moraine on the left edge 

 of the glacier and advancing with it. 



